diff --git a/src/utilities/codemirror/satf/sasf.test.ts b/src/utilities/codemirror/satf/sasf.test.ts
new file mode 100644
index 0000000000..2571b7c44b
--- /dev/null
+++ b/src/utilities/codemirror/satf/sasf.test.ts
@@ -0,0 +1,106 @@
+import { testTree } from '@lezer/generator/test';
+import { describe, expect, test } from 'vitest';
+import { SatfLanguage } from './satf';
+
+const tests = [
+  [
+    'Empty SASF',
+    `
+      $$EOH
+      $$EOD
+      $$EOF
+  `,
+    `satf_sasf(Sasf(
+        Header,
+        Body
+  ))`,
+  ],
+  [
+    'Sample SASF',
+    `
+    $$EOH
+    $$EOD
+        request(VFT2_REQUEST_01,
+        START_TIME, 2024-266T19:59:57,
+        REQUESTOR, "vft2_anichola",
+        PROCESSOR, "VC2AB",
+        KEY, "No_Key")
+
+      command(1,
+        SCHEDULED_TIME,\\00:00:01\\,FROM_PREVIOUS_START,
+        COMMENT,\\"VFT2_short_name  : sada_pause_test_main_seq",
+                "VFT2_full_name   : psy.abs.vc2ab.sada_pause_test_main_seq.r02",
+                "VFT2_onboard_name: sada_pause_test_main_seq",
+                "VFT2_product_type: load_and_go_abs",
+                "VFT2_pce         : AB",
+                "VFT2_vc          : 2",
+                "cumulative_time is     1 sec (2024-266T19:59:58)"\\,
+        FILE_REMOVE("/eng/seq/sada_pause_test_main_seq.abs")
+      )
+      end
+      $$EOF`,
+    `satf_sasf(Sasf(Header,
+      Body(
+      Requests(
+        Request(RequestName,Time,Requestor,Processor,Key,
+        Steps(Command(StepLabel,ScheduledTime(Time,TimeRelation),
+        Comment,Stem,Args(String))))))))`,
+  ],
+  [
+    'Mulitple Requests',
+    `
+    $$EOH
+    $$EOD
+        request(VFT2_REQUEST_01,
+        START_TIME, 2024-266T19:59:57,
+        REQUESTOR, "vft2_anichola",
+        PROCESSOR, "VC2AB",
+        KEY, "No_Key")
+
+      command(1,
+        SCHEDULED_TIME,\\00:00:01\\,FROM_PREVIOUS_START,
+        COMMENT,\\"VFT2_short_name  : sada_pause_test_main_seq",
+                "VFT2_full_name   : psy.abs.vc2ab.sada_pause_test_main_seq.r02",
+                "VFT2_onboard_name: sada_pause_test_main_seq",
+                "VFT2_product_type: load_and_go_abs",
+                "VFT2_pce         : AB",
+                "VFT2_vc          : 2",
+                "cumulative_time is     1 sec (2024-266T19:59:58)"\\,
+        FILE_REMOVE("/eng/seq/sada_pause_test_main_seq.abs")
+      )
+      end,
+      request(VFT2_REQUEST_02,
+        START_TIME, 2024-266T19:59:57,
+        REQUESTOR, "vft2_anichola",
+        PROCESSOR, "VC2AB",
+        KEY, "No_Key")
+
+      command(1,
+        SCHEDULED_TIME,\\00:00:01\\,FROM_PREVIOUS_START,
+        FILE_REMOVE("/test.abs")
+      )
+      end
+      $$EOF`,
+    `satf_sasf(Sasf(Header,Body(
+      Requests(
+        Request(RequestName,Time,Requestor,Processor,Key,
+          Steps(Command(StepLabel,ScheduledTime(Time,TimeRelation),Comment,Stem,Args(String)))),
+        Request(RequestName,Time,Requestor,Processor,Key,
+          Steps(Command(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(String))))
+      )
+    )))`,
+  ],
+];
+
+describe.each([['parse tree structure', tests]])('grammar tests - %s', (_name: string, testArray: string[][]) => {
+  test.each(testArray)('%s', (_: string, input: string, expected: string) => {
+    /* The Lezer parser is "Error-Insensitive"
+    "Being designed for the code editor use case, the parser is equipped with strategies for recovering
+    from syntax errors, and can produce a tree for any input." - (https://lezer.codemirror.net/) as such
+    it always returns a tree, though the tree may have error tokens ("⚠").
+
+    testTree will throw if there's a mismatch between the returned actual and expected trees, it returns
+    undefined when they match. */
+    expect(testTree(SatfLanguage.parser.parse(input), expected, undefined)).toBeUndefined();
+  });
+});
diff --git a/src/utilities/codemirror/satf/satf.test.ts b/src/utilities/codemirror/satf/satf.test.ts
new file mode 100644
index 0000000000..6f87a92282
--- /dev/null
+++ b/src/utilities/codemirror/satf/satf.test.ts
@@ -0,0 +1,866 @@
+import { testTree } from '@lezer/generator/dist/test';
+import { describe, expect, test } from 'vitest';
+import { SatfLanguage } from './satf';
+
+const tests = [
+  [
+    'Empty SATF',
+    `
+      $$EOH
+      $$EOF
+  `,
+    `satf_sasf(Satf(
+        Header,
+        Body
+  ))`,
+  ],
+
+  [
+    'Simple SATF',
+    `
+    CCS3ZF0000100000001NJPL3KS0L015$$MARK$$;
+    MISSION_NAME = TEST;
+    CCSD3RE00000$$MARK$$NJPL3IF0M01400000001;
+    $$TEST     SPACECRAFT ACTIVITY TYPE FILE
+    ************************************************************
+    *PROJECT          TEST
+    *SPACECRAFT       000
+    *Input files used:
+    *File Type	Last modified			File name
+    *SC_MODEL	Thu Jan 01 00:00:00 UTC 1970	/Default Sequence Project/SC_MODEL/
+    ************************************************************
+    $$EOH
+    absolute(temp,\\temp\\)
+    $$EOF
+`,
+    `satf_sasf(Satf(
+    Header(
+      SfduHeader(
+        HeaderPairs(
+          HeaderPair(Key,Value)
+        )
+      ),
+      SeqHeader(
+        Start,
+        LineSeparator,
+        HeaderRecords(
+          HeaderRecord(Keyword,Data),
+          HeaderRecord(Keyword,Data),
+          HeaderRecord(Keyword,Data),
+          HeaderRecord(Keyword,Data),
+          HeaderRecord(Keyword,Data)
+        ),
+        LineSeparator
+      )
+    ),
+    Body(
+      ActivityTypeDefinitions(
+        ActivityTypeGroup(
+          ActivityTypeName,
+          ActivityTypeCode
+        )
+      )
+    )
+  ))`,
+  ],
+
+  [
+    'Header Gone',
+    `
+      $$EOH
+      absolute(temp,\\temp\\)
+      $$EOF
+  `,
+    `satf_sasf(Satf(
+        Header,
+        Body(
+          ActivityTypeDefinitions(
+            ActivityTypeGroup(
+              ActivityTypeName,
+              ActivityTypeCode)
+            )
+          )
+  ))`,
+  ],
+
+  [
+    'Empty SeqHeader Gone',
+    `
+      $$EOH
+      absolute(temp,\\temp\\)
+      $$EOF
+  `,
+    `satf_sasf(Satf(
+        Header,
+        Body(
+          ActivityTypeDefinitions(
+            ActivityTypeGroup(
+              ActivityTypeName,
+              ActivityTypeCode)
+            )
+          )
+  ))`,
+  ],
+
+  [
+    'Multiple Activity Groups',
+    `
+      $$EOH
+      absolute(temp,\\temp\\),
+      absolute(temp,\\temp\\)
+      $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode
+          )
+        ,
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode
+          )
+       )
+      )
+  ))`,
+  ],
+
+  [
+    'Activity Group optional values',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,
+      RETURN_TYPE, \\VOID\\,
+      SEQGEN_AUTO_START_OR_LOAD_TIMES, \\S$BEGIN\\,
+      VIRTUAL_CHANNEL, \\VC2\\,
+      ON_BOARD_FILENAME, \\/tmp/dir/file.seq\\,
+      FLAGS,\\one | two | three\\,
+      HELP,\\this is help text\\,
+      ON_BOARD_PATH,\\path/to/file.txt\\
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            ReturnType,
+            SeqgenText,
+            VirtualChannel,
+            OnBoardFilename,
+            Flags(
+              Flag,
+              Flag,
+              Flag
+            ),
+            Help,
+            OnBoardPath
+          )
+        )
+      )
+  ))`,
+  ],
+
+  [
+    'Activity Group inline optional values',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,RETURN_TYPE, \\VOID\\,ON_BOARD_PATH,   \\path/to/file.txt\\,
+      SEQGEN_AUTO_START_OR_LOAD_TIMES,    \\S$BEGIN\\,
+      HELP,\\this is help text\\,
+          ON_BOARD_FILENAME,\\/tmp/dir/file.seq\\,VIRTUAL_CHANNEL,\\VC2\\,FLAGS,\\one | two | three\\
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            ReturnType,
+            OnBoardPath,
+            SeqgenText,
+            Help,
+            OnBoardFilename,
+            VirtualChannel,
+            Flags(
+              Flag,
+              Flag,
+              Flag
+            )
+          )
+        )
+      )
+  ))`,
+  ],
+
+  [
+    'Parameters',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,
+      PARAMETERS,
+        burn_timeout(
+          TYPE,FLOAT,
+          RANGE,\\135.0...2500.0\\,
+          RANGE, \\10 ... 20\\
+          RANGE, \\20 ... 5\\
+          HELP,\\cool help folks\\
+          DEFAULT,0
+        ),
+        close_lv(
+          TYPE,STRING,
+          ENUM_NAME,\\YES_NO\\,
+          PREFIX,YES
+        ),
+        minimum_momentum_delta(
+          TYPE,FLOAT,
+          RANGE,\\0.1...35.0\\
+          RANGE, \\CLK_DUR:15:05:1 ...CLK_DUR:17:20:0\\
+          RANGE, \\101T12:15:32.512 ...101T10:20:20.123\\
+          RANGE, \\3.4, 0.9, 12.\\,
+        ),
+        Target (
+          TYPE, STRING,
+          RANGE, \\ "J", "I", "E" \\,
+          DEFAULT, "J" ,
+          HELP, \\ Target information for AACS \\ ),
+        end
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            Parameters(
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Help,
+                Default
+              ),
+              Entry(
+                Name,
+                Type,
+                EnumName,
+                Prefix
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Range
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Default,
+                Help
+              )
+            )
+          )
+        )
+      )
+  ))`,
+  ],
+
+  [
+    'Variables',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,
+      VARIABLES,
+        burn_timeout(
+          TYPE,FLOAT,
+          RANGE,\\135.0...2500.0\\,
+          RANGE, \\10 ... 20\\
+          RANGE, \\20 ... 5\\
+          HELP,\\cool help folks\\
+          DEFAULT,0
+        ),
+        close_lv(
+          TYPE,STRING,
+          ENUM_NAME,\\YES_NO\\,
+          PREFIX,YES
+        ),
+        minimum_momentum_delta(
+          TYPE,FLOAT,
+          RANGE,\\0.1...35.0\\
+          RANGE, \\CLK_DUR:15:05:1 ...CLK_DUR:17:20:0\\
+          RANGE, \\101T12:15:32.512 ...101T10:20:20.123\\
+          RANGE, \\3.4, 0.9, 12.\\,
+        ),
+        Target (
+          TYPE, STRING,
+          RANGE, \\ "J", "I", "E" \\,
+          DEFAULT, "J" ,
+          HELP, \\ Target information, for AACS \\ ),
+        end
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            Variables(
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Help,
+                Default
+              ),
+              Entry(
+                Name,
+                Type,
+                EnumName,
+                Prefix
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Range
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Default,
+                Help
+              )
+            )
+          )
+        )
+      )
+  ))`,
+  ],
+
+  [
+    'Variables and Parameters',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,
+      VARIABLES,
+        burn_timeout(
+          TYPE,FLOAT,
+          RANGE,\\135.0...2500.0\\,
+          RANGE, \\10 ... 20\\
+          RANGE, \\20 ... 5\\
+          HELP,\\cool help folks\\
+          DEFAULT,0
+        ),
+        close_lv(
+          TYPE,STRING,
+          ENUM_NAME,\\YES_NO\\,
+          PREFIX,YES
+        ),
+        minimum_momentum_delta(
+          TYPE,FLOAT,
+          RANGE,\\0.1...35.0\\
+          RANGE, \\CLK_DUR:15:05:1 ...CLK_DUR:17:20:0\\
+          RANGE, \\101T12:15:32.512 ...101T10:20:20.123\\
+          RANGE, \\3.4, 0.9, 12.\\,
+        ),
+        Target (
+          TYPE, STRING,
+          RANGE, \\ "J", "I", "E" \\,
+          DEFAULT, "J" ,
+          HELP, \\ Target information for AACS \\ ),
+        end
+      PARAMETERS,
+        burn_timeout(
+          TYPE,FLOAT,
+          RANGE,\\135.0...2500.0\\,
+          RANGE, \\10 ... 20\\
+          RANGE, \\20 ... 5\\
+          HELP,\\cool help folks\\
+          DEFAULT,0
+        ),
+      end,
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            Variables(
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Help,
+                Default
+              ),
+              Entry(
+                Name,
+                Type,
+                EnumName,
+                Prefix
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Range
+              ),
+              Entry(
+                Name,
+                Type,
+                Range,
+                Default,
+                Help
+              )
+            ),
+            Parameters(
+              Entry(
+                Name,
+                Type,
+                Range,
+                Range,
+                Range,
+                Help,
+                Default
+              ),
+            )
+          )
+        )
+      )
+  ))`,
+  ],
+
+  [
+    'Commands',
+    `
+      $$EOH
+        ABSOLUTE_SEQUENCE(test,\\testv01\\,
+          STEPS,
+          command(
+            1,
+            SCHEDULED_TIME,\\00:00:01\\,FROM_PREVIOUS_START,
+            STR_FILES_RM("/eng/seq/ENG_EXEC_b2024288_e2024294.seq")
+          ),
+          command(
+            3472,
+            SCHEDULED_TIME, \\param4\\,
+            FROM_ACTIVITY_START, INCLUSION_CONDITION, \\param_rate == receive_rate\\,
+            DRAW, VERTICAL,
+            COMMENT, \\This command is intended to turn the NIMS to correct position.\\),
+          command (
+            3472, SCHEDULED_TIME, \\param4\\, FROM_ACTIVITY_START, INCLUSION_CONDITION, \\param_rate == receive_rate\\,
+            DRAW, \\VERTICAL\\,
+            COMMENT, \\This command turns the NIMS, to correct position.\\, ASSUMED_MODEL_VALUES, \\x=1,y="abc",z=0.2, Tel::power=1\\,
+            01VV (param6, param7, param8 + param9),
+            PROCESSORS, "PRI", end),
+          command(
+            2,
+            SCHEDULED_TIME,\\00:00:01\\,FROM_PREVIOUS_START,
+            STR_FILES_RM
+          ),
+          end
+        )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header
+      Body(
+        ActivityTypeDefinitions(
+        ActivityTypeGroup(
+          ActivityTypeName,
+          ActivityTypeCode,
+          Steps(
+            Command(
+              StepLabel,
+              ScheduledTime(
+                Time,
+                TimeRelation
+              ),
+              Stem,
+              Args(
+                String
+              )
+            ),
+            Command(
+              StepLabel,
+              ScheduledTime(
+                Time,
+                TimeRelation
+              ),
+              InclusionCondition,
+              Draw,
+              Comment
+            ),
+            Command(
+              StepLabel,
+              ScheduledTime(
+                Time,
+                TimeRelation
+              ),
+              InclusionCondition,
+              Draw,
+              Comment,
+              AssumedModelValues(
+                Model(Key,Value),
+                Model(Key,Value),
+                Model(Key,Value),
+                Model(Key,Value))
+              Stem,
+              Args(
+                Enum,
+                Enum,
+                Arithmetical
+              ),
+              Processors
+            ),
+            Command(
+              StepLabel,
+              ScheduledTime(
+                Time,
+                TimeRelation
+              ),
+              Stem
+            )
+          )
+        )
+      )
+    )
+  )
+  )`,
+  ],
+
+  [
+    'Dynamic Commands',
+    `
+      $$EOH
+      ABSOLUTE_SEQUENCE(test,\\testv01\\,
+          STEPS,
+              Command_dynamic (
+                  3472,
+                  SCHEDULED_TIME, \\param4\\, FROM_ACTIVITY_START,
+                  INCLUSION_CONDITION, \\param_rate == receive_rate\\,
+                  DRAW, \\VERTICAL\\,
+                  NTEXT, \\"This command turns the NIMS to correct position."\\,
+                  COMMENT, \\This command turns the NIMS to correct position.\\, "01vv" (param6, param7, a+b),
+                  PROCESSORS, "PRI", end
+              ),
+              Command_dynamic (
+                  3472, SCHEDULED_TIME, \\param4\\, FROM_ACTIVITY_START,
+                  "01vv",
+                  PROCESSORS, end ),
+          end
+      )
+      $$EOF
+  `,
+    `satf_sasf(Satf(
+      Header,
+      Body(
+        ActivityTypeDefinitions(
+          ActivityTypeGroup(
+            ActivityTypeName,
+            ActivityTypeCode,
+            Steps(
+              CommandDynamic(
+                StepLabel,
+                ScheduledTime(
+                  Time,
+                  TimeRelation
+                ),
+                InclusionCondition,
+                Draw,
+                Ntext,
+                Comment,
+                Stem,
+                Args(
+                  Enum,
+                  Enum,
+                  Arithmetical
+                ),
+                Processors
+              ),
+              CommandDynamic(
+                StepLabel,
+                ScheduledTime(
+                  Time,
+                  TimeRelation
+                ),
+                Stem
+              )
+            )
+          )
+        )
+      )
+    )
+  )`,
+  ],
+
+  [
+    'Notes',
+    `
+      $$EOH
+      ABSOLUTE_SEQUENCE(test,\\testv01\\,
+          STEPS,
+              note (
+                  327.1, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START,
+                  TEXT, \\"Cmd 06VV22 will be issued at"+TIME_TO_STRING(param_time)\\
+              ),
+              note (2,
+              SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START, INCLUSION_CONDITION, \\param_rate == receive_rate\\,
+              DRAW, \\STANDARD\\, COMMENT, \\This informs the flight team, about this command.\\, TEXT, \\"Cmd 06VV22 will be issued at"+TIME_TO_STRING(param_time)\\ ),
+          end
+      )
+    $$EOF
+  `,
+    `satf_sasf(Satf(
+    Header,
+    Body(
+      ActivityTypeDefinitions(
+        ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,Steps(
+          Note(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Expression)),
+          Note(StepLabel,ScheduledTime(Time,TimeRelation),InclusionCondition,Draw,Comment,Stem,Args(Expression))))))))`,
+  ],
+
+  [
+    'Activate',
+    `
+      $$EOH
+      ABSOLUTE_SEQUENCE(test,\\testv01\\,
+          STEPS,
+              activity (3, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START, INCLUSION_CONDITION, \\param_one <= symbol_range\\,
+                  DRAW, \\HORIZONTAL\\,
+                  COMMENT, \\This is an example of a SEQGEN directive.\\,
+                  SEQGEN_directive(MODEL,"my_model")
+              ),
+              activity (3, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START,
+                  SEQGEN_directive(SSF_BEGIN,"my_SSF", "123", "My sequence") ),
+              activity (3, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START,
+                  COMMENT, \\This is an example of a SEQTRAN_SETR directive.\\,
+                  SEQTRAN_SETR(macro,"abc", "123", "5,123,OP")
+              ),
+              activity (3, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START,
+              SEQTRAN_directive(WINDOW,"abc", "123",
+              "5,123,OP") ),
+              activity (3, SCHEDULED_TIME, \\param_time\\, FROM_PREVIOUS_START, SEQTRAN_directive(SEQEND))
+          end
+      )
+      $$EOF
+  `,
+    `satf_sasf(Satf(Header,Body(ActivityTypeDefinitions(ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,Steps(
+      Activity(StepLabel,ScheduledTime(Time,TimeRelation),InclusionCondition,Draw,Comment,
+        Group(TypeGroup,TypeName,Name)),
+      Activity(StepLabel,ScheduledTime(Time,TimeRelation),
+        Group(TypeGroup,TypeName,Filename,SeqId,Title)),
+      Activity(StepLabel,ScheduledTime(Time,TimeRelation),Comment,
+        Group(TypeGroup,TypeName,Label,Opcode,Pars)),
+      Activity(StepLabel,ScheduledTime(Time,TimeRelation),
+        Group(TypeGroup,TypeName,Args(String,String,String))),
+      Activity(StepLabel,ScheduledTime(Time,TimeRelation),
+        Group(TypeGroup,TypeName))))))))`,
+  ],
+
+  [
+    'Loops',
+    `
+    $$EOH
+    ABSOLUTE_SEQUENCE(test,\\testv01\\,
+        STEPS,
+            loop (
+                14.2, SCHEDULED_TIME, \\0\\, FROM_ACTIVITY_START,
+                COMMENT, \\Example of a loop structure for the SEQGEN program.\\,
+                COUNT, \\param_count\\
+            ),
+            command (
+                245, SCHEDULED_TIME, \\param_time + param_offset\\, FROM_PREVIOUS_START,
+                4GLS22 (param6, param8, param7 + param9), PROCESSORS,end
+            ),
+            command (
+                327, SCHEDULED_TIME, \\param_time *param_offset\\,FROM_PREVIOUS_START,
+                4GLS33
+            ),
+            end_loop (
+                247, SCHEDULED_TIME, \\param_time + param_delta\\, FROM_PREVIOUS_START),
+        end
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(Header,Body(ActivityTypeDefinitions(ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,
+      Steps(
+        Loop(StepLabel,ScheduledTime(Time,TimeRelation),Comment,
+          Count,
+          Steps(
+            Command(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Enum,Enum,Arithmetical)),
+            Command(StepLabel,ScheduledTime(Time,TimeRelation),Stem)
+          ),
+          EndLoop,StepLabel,ScheduledTime(Time,TimeRelation)
+  )))))))`,
+  ],
+
+  [
+    'Assignment',
+    `
+    $$EOH
+        ABSOLUTE_SEQUENCE(test,\\testv01\\,
+            STEPS,
+                assignment(326, SCHEDULED_TIME, \\param2 + param3\\, FROM_ACTIVITY_START,
+                PHASE,
+                \\3.14\\),
+        end
+    )
+    $$EOF
+  `,
+    `satf_sasf(Satf(Header,Body(ActivityTypeDefinitions(ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,
+      Steps(
+        Assignment(StepLabel,ScheduledTime(Time,TimeRelation),
+          Variable,Args(Number)
+  )))))))`,
+  ],
+
+  [
+    'Ground Event',
+    `
+     $$EOH
+        ABSOLUTE_SEQUENCE(test,\\testv01\\,
+            STEPS,
+                ground (3472, SCHEDULED_TIME, \\param4\\, FROM_ACTIVITY_START, INCLUSION_CONDITION, \\param_rate == receive_rate\\,
+                  COMMENT, \\Occurs at the maximum elevation of the station.\\, max_elevation(ELEV)),
+                ground (3472, SCHEDULED_TIME, \\00:01:01\\, FROM_ACTIVITY_START, fire_booster(10.0))
+        end
+      )
+    $$EOF
+  `,
+    `satf_sasf(Satf(Header,Body(ActivityTypeDefinitions(ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,Steps(
+      Ground(StepLabel,ScheduledTime(Time,TimeRelation),InclusionCondition,Comment,Stem,Args(Enum)),
+      Ground(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Number))
+  ))))))`,
+  ],
+
+  [
+    'sample satf',
+    `
+    $$EOH
+    RT_on_board_block(test_block, test_block,
+        RETURN_TYPE,\\\\, HELP,\\Just a test\\,
+        PARAMETERS,
+            P1(
+                TYPE, \\INTEGER\\,
+                RANGE, \\1 ... 50\\,
+                DEFAULT, \\10\\,
+                HELP, \\Controls number of loops\\
+            ),
+            D1(
+                TYPE, \\DURATION\\
+            ),
+        end,
+        VARIABLES,
+            T(
+                TYPE, \\TIME\\,
+                DEFAULT, \\2000-001T00:00:00.000\\
+            ), count(
+                TYPE, \\INTEGER\\,
+                DEFAULT, \\0\\
+            ),
+            wait_flag1(
+                TYPE, \\INTEGER\\,
+                DEFAULT, \\0\\
+            ),
+            wait_flag2(
+                TYPE, \\BOOLEAN\\,
+                DEFAULT, \\TRUE\\
+            ),
+            V1(
+                TYPE, \\STRING\\,
+                DEFAULT, \\""\\
+            ),
+        end,
+        STEPS,
+            command(1,
+                SCHEDULED_TIME, \\0:00:00\\, FROM_PREVIOUS_END, COMMENT, \\First cmd\\,
+                RW_1_PWR("OFF")
+            ),
+            command(6,
+                SCHEDULED_TIME, 0:00:00, FROM_PREVIOUS_END, COMMENT, \\\\,
+                UHF_POWER()
+            ),
+        end
+    ),
+
+    RT_on_board_block(GV_control, GV_control, RETURN_TYPE,\\d\\,
+        HELP,\\Just a test\\,
+        PARAMETERS,
+            D1(
+                TYPE, \\DURATION\\
+            ),
+        end,
+        STEPS,
+            note(5,
+                SCHEDULED_TIME,00:00:00,FROM_PREVIOUS_END,
+                TEXT, \\"GV::GV_SPARE_21 should be set to 2 now"\\ ),
+            note(7,
+            SCHEDULED_TIME,00:00:00,FROM_PREVIOUS_END,
+            TEXT, \\"GV::GV_SPARE_22 should be set to 0 now"\\
+            ),
+            command(3, SCHEDULED_TIME,00:00:00,FROM_PREVIOUS_END, ECHO(global::blah))
+            end)
+    $$EOF
+  `,
+    `satf_sasf(Satf(Header,Body(ActivityTypeDefinitions(
+      ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,Help,
+        Parameters(Entry(Name,Type,Range,Default,Help),Entry(Name,Type)),Variables(Entry(Name,Type,Default),Entry(Name,Type,Default),Entry(Name,Type,Default),Entry(Name,Type,Default),Entry(Name,Type,Default)),
+        Steps(
+          Command(StepLabel,ScheduledTime(Time,TimeRelation),Comment,Stem,Args(String)),
+          Command(StepLabel,ScheduledTime(Time,TimeRelation),Stem))),
+      ActivityTypeGroup(ActivityTypeName,ActivityTypeCode,ReturnType,Help,
+        Parameters(Entry(Name,Type)),
+        Steps(
+          Note(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Expression)),
+          Note(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Expression)),
+          Command(StepLabel,ScheduledTime(Time,TimeRelation),Stem,Args(Global))
+  ))))))`,
+  ],
+];
+
+describe.each([['parse tree structure', tests]])('grammar tests - %s', (_name: string, testArray: string[][]) => {
+  test.each(testArray)('%s', (_: string, input: string, expected: string) => {
+    /* The Lezer parser is "Error-Insensitive"
+    "Being designed for the code editor use case, the parser is equipped with strategies for recovering
+    from syntax errors, and can produce a tree for any input." - (https://lezer.codemirror.net/) as such
+    it always returns a tree, though the tree may have error tokens ("⚠").
+
+    testTree will throw if there's a mismatch between the returned actual and expected trees, it returns
+    undefined when they match. */
+    expect(testTree(SatfLanguage.parser.parse(input), expected, undefined)).toBeUndefined();
+  });
+});