diff --git a/src/back/spv/layout.rs b/src/back/spv/layout.rs
index 40e3e47e9e..5db9a05caa 100644
--- a/src/back/spv/layout.rs
+++ b/src/back/spv/layout.rs
@@ -3,7 +3,7 @@ use spirv::*;
 use std::iter;
 
 impl PhysicalLayout {
-    pub(crate) fn new(header: &crate::Header) -> Self {
+    pub(super) fn new(header: &crate::Header) -> Self {
         let version: Word = ((header.version.0 as u32) << 16)
             | ((header.version.1 as u32) << 8)
             | header.version.2 as u32;
@@ -17,7 +17,7 @@ impl PhysicalLayout {
         }
     }
 
-    pub(crate) fn in_words(&self, sink: &mut impl Extend<Word>) {
+    pub(super) fn in_words(&self, sink: &mut impl Extend<Word>) {
         sink.extend(iter::once(self.magic_number));
         sink.extend(iter::once(self.version));
         sink.extend(iter::once(self.generator));
@@ -27,7 +27,7 @@ impl PhysicalLayout {
 }
 
 impl LogicalLayout {
-    pub(crate) fn in_words(&self, sink: &mut impl Extend<Word>) {
+    pub(super) fn in_words(&self, sink: &mut impl Extend<Word>) {
         sink.extend(self.capabilities.iter().cloned());
         sink.extend(self.extensions.iter().cloned());
         sink.extend(self.ext_inst_imports.iter().cloned());
@@ -43,7 +43,7 @@ impl LogicalLayout {
 }
 
 impl Instruction {
-    pub(crate) fn new(op: Op) -> Self {
+    pub(super) fn new(op: Op) -> Self {
         Instruction {
             op,
             wc: 1, // Always start at 1 for the first word (OP + WC),
@@ -53,30 +53,30 @@ impl Instruction {
         }
     }
 
-    pub(crate) fn set_type(&mut self, id: Word) {
+    pub(super) fn set_type(&mut self, id: Word) {
         assert!(self.type_id.is_none(), "Type can only be set once");
         self.type_id = Some(id);
         self.wc += 1;
     }
 
-    pub(crate) fn set_result(&mut self, id: Word) {
+    pub(super) fn set_result(&mut self, id: Word) {
         assert!(self.result_id.is_none(), "Result can only be set once");
         self.result_id = Some(id);
         self.wc += 1;
     }
 
-    pub(crate) fn add_operand(&mut self, operand: Word) {
+    pub(super) fn add_operand(&mut self, operand: Word) {
         self.operands.push(operand);
         self.wc += 1;
     }
 
-    pub(crate) fn add_operands(&mut self, operands: Vec<Word>) {
+    pub(super) fn add_operands(&mut self, operands: Vec<Word>) {
         for operand in operands.into_iter() {
             self.add_operand(operand)
         }
     }
 
-    pub(crate) fn to_words(&self, sink: &mut impl Extend<Word>) {
+    pub(super) fn to_words(&self, sink: &mut impl Extend<Word>) {
         sink.extend(Some((self.wc << 16 | self.op as u32) as u32));
         sink.extend(self.type_id);
         sink.extend(self.result_id);
diff --git a/src/back/spv/layout_tests.rs b/src/back/spv/layout_tests.rs
index 697b609fac..37024b238f 100644
--- a/src/back/spv/layout_tests.rs
+++ b/src/back/spv/layout_tests.rs
@@ -1,3 +1,4 @@
+use crate::back::spv::test_framework::*;
 use crate::back::spv::{helpers, Instruction, LogicalLayout, PhysicalLayout};
 use crate::Header;
 use spirv::*;
@@ -76,7 +77,7 @@ fn test_logical_layout_in_words() {
     for instruction in instructions {
         let wc = instruction.wc as usize;
         let instruction_output = &output[index..index + wc];
-        validate_instruction(instruction_output, instruction);
+        validate_instruction(instruction_output, &instruction);
         index += wc;
     }
 }
@@ -157,32 +158,7 @@ fn test_instruction_to_words() {
 
     let mut output = vec![];
     instruction.to_words(&mut output);
-    validate_instruction(output.as_slice(), instruction);
-}
-
-fn validate_instruction(words: &[Word], instruction: Instruction) {
-    let mut inst_index = 0;
-    let (wc, op) = ((words[inst_index] >> 16) as u16, words[inst_index] as u16);
-    inst_index += 1;
-
-    assert_eq!(wc, words.len() as u16);
-    assert_eq!(op, instruction.op as u16);
-
-    if instruction.type_id.is_some() {
-        assert_eq!(words[inst_index], instruction.type_id.unwrap());
-        inst_index += 1;
-    }
-
-    if instruction.result_id.is_some() {
-        assert_eq!(words[inst_index], instruction.result_id.unwrap());
-        inst_index += 1;
-    }
-
-    let mut op_index = 0;
-    for i in inst_index..wc as usize {
-        assert_eq!(words[i as usize], instruction.operands[op_index]);
-        op_index += 1;
-    }
+    validate_instruction(output.as_slice(), &instruction);
 }
 
 fn to_word(bytes: &[u8]) -> Word {
diff --git a/src/back/spv/mod.rs b/src/back/spv/mod.rs
index 468307f55d..4c3ca33626 100644
--- a/src/back/spv/mod.rs
+++ b/src/back/spv/mod.rs
@@ -2,6 +2,9 @@ mod helpers;
 mod layout;
 mod writer;
 
+#[cfg(test)]
+mod test_framework;
+
 #[cfg(test)]
 mod layout_tests;
 
@@ -25,7 +28,7 @@ struct PhysicalLayout {
 }
 
 #[derive(Default)]
-pub(crate) struct LogicalLayout {
+struct LogicalLayout {
     capabilities: Vec<Word>,
     extensions: Vec<Word>,
     ext_inst_imports: Vec<Word>,
@@ -39,7 +42,7 @@ pub(crate) struct LogicalLayout {
     function_definitions: Vec<Word>,
 }
 
-struct Instruction {
+pub(self) struct Instruction {
     op: Op,
     wc: u32,
     type_id: Option<Word>,
diff --git a/src/back/spv/test_framework.rs b/src/back/spv/test_framework.rs
new file mode 100644
index 0000000000..332d300a4d
--- /dev/null
+++ b/src/back/spv/test_framework.rs
@@ -0,0 +1,58 @@
+use crate::back::spv::Instruction;
+use spirv::{Op, Word};
+
+pub(super) struct SpecRequirements {
+    pub(super) op: Op,
+    pub(super) wc: u32,
+    pub(super) type_id: bool,
+    pub(super) result_id: bool,
+    pub(super) operands: bool,
+}
+
+/// Basic validation for checking if the instruction complies to the spec requirements
+pub(super) fn validate_spec_requirements(
+    requirements: SpecRequirements,
+    instruction: &Instruction,
+) {
+    assert_eq!(requirements.op, instruction.op);
+
+    // Pass the assert if the minimum referred wc in the spec is met
+    assert!(instruction.wc >= requirements.wc);
+
+    if requirements.type_id {
+        assert!(instruction.type_id.is_some());
+    }
+
+    if requirements.result_id {
+        assert!(instruction.result_id.is_some());
+    }
+
+    if requirements.operands {
+        assert!(!instruction.operands.is_empty());
+    }
+}
+
+pub(super) fn validate_instruction(words: &[Word], instruction: &Instruction) {
+    let mut inst_index = 0;
+    let (wc, op) = ((words[inst_index] >> 16) as u16, words[inst_index] as u16);
+    inst_index += 1;
+
+    assert_eq!(wc, words.len() as u16);
+    assert_eq!(op, instruction.op as u16);
+
+    if instruction.type_id.is_some() {
+        assert_eq!(words[inst_index], instruction.type_id.unwrap());
+        inst_index += 1;
+    }
+
+    if instruction.result_id.is_some() {
+        assert_eq!(words[inst_index], instruction.result_id.unwrap());
+        inst_index += 1;
+    }
+
+    let mut op_index = 0;
+    for i in inst_index..wc as usize {
+        assert_eq!(words[i as usize], instruction.operands[op_index]);
+        op_index += 1;
+    }
+}
diff --git a/src/back/spv/writer.rs b/src/back/spv/writer.rs
index 4124280d2d..3757f8fdd6 100644
--- a/src/back/spv/writer.rs
+++ b/src/back/spv/writer.rs
@@ -646,11 +646,9 @@ impl Writer {
         self.physical_layout.bound = self.id_count + 1;
     }
 
-    fn instruction_source(&self) -> Instruction {
-        let version = 450u32;
-
+    fn instruction_source(&self, source_language: SourceLanguage, version: u32) -> Instruction {
         let mut instruction = Instruction::new(Op::Source);
-        instruction.add_operand(SourceLanguage::GLSL as u32);
+        instruction.add_operand(source_language as u32);
         instruction.add_operands(helpers::bytes_to_words(&version.to_le_bytes()));
         instruction
     }
@@ -923,7 +921,8 @@ impl Writer {
             .to_words(&mut self.logical_layout.ext_inst_imports);
 
         if self.writer_flags.contains(WriterFlags::DEBUG) {
-            self.debugs.push(self.instruction_source());
+            self.debugs
+                .push(self.instruction_source(SourceLanguage::GLSL, 450));
         }
 
         for (handle, function) in ir_module.functions.iter() {
@@ -1000,3 +999,166 @@ impl Writer {
         words
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::back::spv::test_framework::*;
+    use crate::back::spv::{Writer, WriterFlags};
+    use crate::Header;
+    use spirv::*;
+
+    #[test]
+    fn test_writer_generate_id() {
+        let mut writer = create_writer();
+
+        assert_eq!(writer.id_count, 0);
+        writer.generate_id();
+        assert_eq!(writer.id_count, 1);
+    }
+
+    #[test]
+    fn test_try_add_capabilities() {
+        let mut writer = create_writer();
+
+        assert_eq!(writer.capabilities.len(), 0);
+        writer.try_add_capabilities(&[Capability::Shader]);
+        assert_eq!(writer.capabilities.len(), 1);
+
+        writer.try_add_capabilities(&[Capability::Shader]);
+        assert_eq!(writer.capabilities.len(), 1);
+    }
+
+    #[test]
+    fn test_instruction_capability() {
+        let writer = create_writer();
+        let instruction = writer.instruction_capability(Capability::Shader);
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::Capability,
+            wc: 2,
+            type_id: false,
+            result_id: false,
+            operands: true,
+        };
+
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_instruction_ext_inst_import() {
+        let mut writer = create_writer();
+        let import_name = "GLSL.std.450";
+        let instruction = writer.instruction_ext_inst_import(import_name);
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::ExtInstImport,
+            wc: 2,
+            type_id: false,
+            result_id: true,
+            operands: true,
+        };
+
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_instruction_memory_model() {
+        let mut writer = create_writer();
+        let instruction = writer.instruction_memory_model();
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::MemoryModel,
+            wc: 3,
+            type_id: false,
+            result_id: false,
+            operands: true,
+        };
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_instruction_source() {
+        let writer = create_writer();
+        let version = 450;
+        let instruction = writer.instruction_source(SourceLanguage::GLSL, version);
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::Source,
+            wc: 3,
+            type_id: false,
+            result_id: false,
+            operands: true,
+        };
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_instruction_label() {
+        let mut writer = create_writer();
+        let instruction = writer.instruction_label();
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::Label,
+            wc: 2,
+            type_id: false,
+            result_id: true,
+            operands: false,
+        };
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_instruction_function_end() {
+        let writer = create_writer();
+        let instruction = writer.instruction_function_end();
+        let mut output = vec![];
+
+        let requirements = SpecRequirements {
+            op: Op::FunctionEnd,
+            wc: 1,
+            type_id: false,
+            result_id: false,
+            operands: false,
+        };
+        validate_spec_requirements(requirements, &instruction);
+
+        instruction.to_words(&mut output);
+        validate_instruction(output.as_slice(), &instruction);
+    }
+
+    #[test]
+    fn test_write_physical_layout() {
+        let mut writer = create_writer();
+        assert_eq!(writer.physical_layout.bound, 0);
+        writer.write_physical_layout();
+        assert_eq!(writer.physical_layout.bound, 1);
+    }
+
+    fn create_writer() -> Writer {
+        let header = Header {
+            generator: 0,
+            version: (1, 0, 0),
+        };
+        Writer::new(&header, WriterFlags::NONE)
+    }
+}